ISLAMABAD United Nations on Tuesday warned of two second waves of disaster to engulf the flood-hit region if emergency arrangements are not made to address the humanitarian situation. In a joint press conference, the top officials of United Nations Children Fund (UNICEF), United Nations World Food Programme (WFP) and United Nations Educational, Scientific and Cultural Organisation (UNESCO) and Special Envoy to UN Secretary General for Assistance to Pakistan Jean-Maurice Ripert, cautioned that humanitarian challenges in the flood-hit areas were grave and required adequate emergency response. This is the largest humanitarian crisis in a decade. As many as 17.6 million are affected by floods of which 8.6 million children are vulnerable to diseases, Anthony Lake, Executive Director UNICEF, said, adding that 6 million women and children urgently needed clean drinking water and sanitation. We fear two second waves as high floods reach southern parts of Pakistan. This flood wave is disastrous. The second wave of waterborne diseases is likely to spread across children. We must act now and prevent this from happening, he added. What I saw today has convinced me that we must step up our humanitarian operations to stave off a potential second wave of disease and misery for millions of families, especially the most vulnerable, children and women. We are here today and for the long-term, as we plan for the early recovery phase of the operation, Lake said. Josette Sheeran, Executive Director WFP, said, There is a triple threat unfolding as this crisis widens and deepens. People have lost seeds, crops and their incomes leaving them vulnerable to hunger, homelessness and desperation - the situation is extremely critical. We urgently need continued and strengthened commitment to the people of Pakistan in this time of crisis. She said WFP needed $ 90 million for food supply across the flood-hit areas and it would launch an appeal of $ 40 million soon, to ensure unhindered food supply to the affectees. Sheeran said WFP had one month ration to reach out to 3 million people. According to the WFP official, 40 airlifts were needed to access the flood affectees in worst hit areas. Jean Maurice Ripert said, The world has now understood this catastrophe is beyond imagination that took place anywhere in the world. He reiterated international communitys resolve to stand by Pakistan. In Germany alone, the people collected $ 50 million for Pakistans flood affectees, what I mean to say is Pakistan is not alone and UN and international community stand united to fight these floods, he added. Director General UNESCO, Irina Bokova, said that UNESCO was assessing damages done to livelihood and it would be working with communities and other humanitarian partners to pay due heed to the plight of flood victims.